Hi. I’ve bought this SI470x evaluation board clone and i would like to add an external antenna to it.
The reason why i have this antenna, is because before settling on this module for my FM Radio project, I’ve tried using the RDA5807M module (which requires external antenna), and i broke 2 of those boards because of my low quality soldering equipment.
Still, i want to make use of this antenna though. And i’ve done digging on the internet. One method is to isolate the FMIP capacitor, though it required some trace cutting and precision soldering, which isn’t something i’m good at. Another one, is to solder the antenna directly into the headphone jack’s ground pin, but i’m not sure about that and needed more explaination.
Thanks in advance
It might be worth having someone else perform the soldering for you (places like phone or electronics repair, drone shops, some schools/libraries, maker spaces, friends) and see how that goes
Solder your antenna or a 30" long piece of wire to the terminal marked by the arrow.
You could also use a 5’ headphone extension cable plugged into the jack, the cable will act as an antenna.
Thanks, i’ll try. Now, my module has a rectangular headphone jack package, not a circular one, with exposed terminals on the bottom. Where should i solder on?
I have no idea, that’s not the board you said you purchased.
Well, yes i did not buy on the sparkfun website… it was a clone with the same circuit as sparkfun’s. This clone is based off an older revision, which was long since discontinued. Here is the shopping page of the board, dated 2019
if you need the schematic diagram of this board, here it is: https://web.archive.org/web/20201028210117/https://www.sparkfun.com/datasheets/BreakoutBoards/Si470x-Eval-v11.pdf
Looking at the schematics, the antenna system is the same as the new revision’s
It’s probably that single terminal in the center of the connector but a headphone extension cable will also work.
Well, yes i can confirm. Used my multimeter’s continuity feature, pressed one lead to the FMIP capacitor and the middle terminal, and the multimeter beeped. So, i suppose i’ll just solder a wire between the ground sleeve and my telescopic antenna
I did just that. The problem is… the reception is absolutely terrible. Most the audio is quiet static or low volume live radio. There is this one special thing in my circuit, is that i’m using external speakers through the PAM8403 amplifier
If you’re concerned the soldering might still be the issue you can share a photo of the area and we can assess if it looks viable
Thanks, but my earlier soldering problems are caused by bad solder selection, those that require very high temperatures to melt. My soldering experience has been much better now. My antenna (which by the way is fundamentally just a long wire) is connected to the ground output on my male headphone jack breakout module. The reception is terrible though… most of the audio is static. And also, since i’m using external speakers as output, external antenna is required, because the wires to the amplifier are short
Try with just headphones and see if reception is any better.
